Possibly the Greatest Alchemist of All Time

Due to a careless mistake, god of wind Silphyleel unintentionally kills a 28-year-old man named Takumi Kayano. Unfortunately, Silphyleel cannot return Takumi to Earth. Instead, the deity reincarnates Takumi into the fantasy world of Etelldia. Equipped with an assortment of magical powers and bottomless inventory, Takumi spawns in the Forest of Gaia, where high-level monsters roam free. There, he meets five-year-old twins who, despite the dangerous environment, are still alive thanks in part to their extraordinary physical strength. Takumi decides to take them under his wing, naming them Allen and Elena. As the trio embarks on their grand adventure in Etelldia, their very existence may impact the world's destiny.